Process of making halohydrins



Cl-and OH-radicals erine halohydrins may ter used be 9 resulting inPatented Aug. 3, 1926.

UNITED STATES PATENT OFFICE.

HARRY ESSEX AND ALGEB L. WARD,

IOBATION OF DELAWARE.

rnoonss or No Drawing.

This invention relates to a process of making from a substitutedpropylene halohydrins suitable for conversion into glycerine,

and comprises inducing a reaction between 6 water, chlorine, and saidsubstituted propylene ata low temperature.

One object of this invention is to provide an eflicient and inexpensiveprocess of obtaining dichlorhydrins which may be em- 10 ployed insynthesizing glycerine.

Another object of this invention is to provide an improved process ofconverting allyl halides into the corresponding glycerine halohydrins bythe chemical addition of the of hypochlorous *acid, in order to renderthis reaction comme'rcially feasible as a step towards the manufactureof glycerine.

According to the present invention, glycbe readily. and cheaply preparedand with high yields by the simple procedure of passing chlorine into anagitated and cooled mixture of an allyl The reaction is complete color.In order that concentrated solutions of halohydrins be formed, or, inthe case of sparingly soluble halohydrins, in .order that the ratio ofhalohydrin produced to the wahigh, it is desirable that the solution,which normally increases in acidity with the progress of the; reaction,be neutralized from time to time.

The temperature of the reaction mixture should be kept low andpreferably below- 20 C. throughout the operation. We have found that athigh temperatures'the reaction between water, chlorine and allyl halidesis infiuenced in undesirable directions, the formation of considerablequantities of trihalogenhydrins and higher substituted'products. In anexperiment in which water at the boiling point was treated with allylchloride and chlorine, the yield of dichlorhydrins was very low, whichresult may be attributed to the recognized 1nstability of hypochlorousacid at this temerature. If allyl chloride be used the principal re- OFWILMINGTON, E. I. DU PONT .DENEMOURS & COMPANY,

OF WILMINGTON, DELAWARE, A COB- MAKING HALOH'YDRINS.

. Application filed November 22, 1919- Serial No. 340,074.

action which takes place may be represented by the equation:--

on oioi-ronou d are formed at the same time. Both of thesedichlorhydrins are suitable for the production of glycerine. Glycerine'1, 2, 3-trichlorhydrin is diflicult toconvert to glycerine, but is notformed to any extent in operating in the indicated manner, provided thetemperature conditions specified are observed and provided it is notattempted to push the ratio of chlorhydrin produced to water used, toextreme limits.

It will be noted that by employing chlorine gas instead of hypochlorousacid th formation of additional water is avoided with the resultingimportant advantage that the dichlorhydrins are precipitated in asaturated solution and may be collected in undiluted form withoutfurther separation or purification. v

Allyl halides suitable for the herein described synthesis of glycerinemay be-readily prepared by passing the vapors of dihal- 'ogenpropanesover hot calcium chloride.

However, allyl halides, by whatever means prepared, are suitable as rawmaterials for'this synthesis of glycerine and we, therefore, do notlimit ourselves to allyl halides from the above source.

We have found that glycerine-monochlorand dichlorhydrins are readilyhydrolyzable to glycerine and with high yields, differing in thisrespect' from the 'trichlorhydrin which'has been repeatedly suggested asan intermediate for the synthesis of glycerine and which was used in theclassical glycerine synthesis of Friedel and Silva. Our experience hasshown that Whereas it is difficult to obtain yields of 'gly cerinehigher than 20% by hydrolysis of the trichlorhydrin, yields in excess of90% may be readily obtained by hydrolysis of the mixtures ofdichlorhydrins or of the mixture of mono- DELAWARE, ASSIGNORS TOchlorhydrins, obtained by the addition of ate, in an amount sufficientto facilitate the component radicals of hypochlorous acid hydrolysis andheating the mixture until to allyl chloride or allyl alcoholrespectively. hydrolysis is substantially completed; this is .n theembodiment of our invention parpreferably done by raising thetemperature ticularly advantageous, chlorine is passed of the reactionmixture to approximately into a cool agitated mixture of allyl chloride100 C., and maintaining it at this temperand Water, the resultinghydrochloric acid ature for severalhours. If desired the adbeingneutralized from time to time, until dition of an alkaline-reactingsubstance may the allyl chloride has almost or completely be omitted,but in this case the heating must 10 reacted, as indicated by apersistent yellow be continued for a longer period.

color of the solution. A small quantityof We claim v allyl chloride isthen added to the solution The process of making dichlorhydrin to reactwith any excess chlorine which may which comprises precipitating thesame by be present. The dichlorhydrins formed in passing gaseouschlorine into a mixture of 15 this reaction are somewhat soluble inWater allyl chloride and a saturated Water soluand remain dissolveduntil their continued tion of dichlorhydrin whereby the dichlorformationresults in a saturated solution. hydrins are collected separately fromthe The dichlorhydrins produced after the point mixture. of saturationis reached separate from the In testimony whereof We aflix oursignasolution as an almost colorless oil. tures. v

The conversion to glycerine is easily ef fected simply by adding analkaline-reacting HARRY ESSEX. substance, as slaked lime or sodiumcarbon ,ALGER L. WARD.

